Phosphorylation of tyrosine residues is a central feature of most cellular signaling pathways, including those affecting growth, differentiation, cell cycle regulation, apoptosis and invasion (1, 2). This phosphorylation is coordinately controlled by protein tyrosine kinases (PTKs) and phosphatases (PTPs). Although a variety of PTK genes have been directly linked to tumorigenesis through somatic activating mutations (3-6) only a few PTP genes have been implicated in cancer (7-10). Moreover, it is not known how many or how frequently members of the PTP gene family are altered in any particular cancer type.
The PTP gene superfamily is composed of three main families: (i) the classical PTPs, including the receptor PTPs (RPTPs) and the non-receptor PTPs (NRPTPs); (ii) the dual specificity phosphatases (DSPs), which can dephosphorylate serine and threonine in addition to tyrosine residues; and (iii) the low molecular weight phosphatases (LMPs) (1).
There is a continuing need in the art to identify new therapeutic targets, identify new drugs, improve diagnosis, prognosis, and therapy of cancers.